If a worshipper forgetfully omits the Qunut in the third rak'ah of Witr and remembers it while in bowing (Ruku'), what should they do?

The Witr Prayer: Rulings, Qunut, and Congregation

• They must stand back up immediately, recite the Qunut, and repeat the bowing.
• They must continue their bowing, omit the Qunut recitation, and perform Sujud al-Sahw at the end of the prayer.
• The prayer is completely broken and they must restart.
• They must recite the Qunut silently while bowing.